Signposting: modelling uncertainty in design processes

In engineering design, there is often considerable uncertainty in knowledge about the product, for example, the lift generated by a wing might be unknown until wind tunnel tests have been performed. Equally, at the start of a design project, there is considerable uncertainty about the direction the process will take, which tools will be necessary, which tasks will be successful, which aspects of the design requirements will be difficult to meet. This process uncertainty causes difficulty in planning engineering design projects, and in managing these projects during their execution. Existing process modelling tools represent processes on a high level, as well as only a subset of the possible variations in a design project, neglecting such factors as non essential information transfer, use of alternative tools or methods, and the effect of assigning different engineers to different tasks. This paper presents the most recent iteration of the Signposting system, which has been developed in Cambridge to provide a framework for engineering design process modelling. Such a framework must meet a number of requirements which are discussed, and the performance of the Signposting framework against these metrics is assessed. The practicalities of building models in industry using this framework are discussed, and an number of model building protocols are introduced.